Add an Item Pass Rate chart to the Pathway dashboard

User Story

As an administrator or course team member, I want to see the pass rates plotted for each currently-filtered pathway item, so I can easily identify items that learners have trouble passing that need further review

Acceptance Criteria

Description: An Item Pass Rate bar chart has been added to the Item Completion section.
Given I am a user with access to the Pathway Dashboard
When I view the Item Completion section
Then I see a bar chart showing the pass rate for each pathway item on the, among learners who started that item, calculated as (N of learners who have passed the item in the pathway / N of learners enrolled in pathway) x 100 on the Y axis and Item on the X axis (of the currently filtered Pathways)

Start by locating the Pathway Dashboard's Item Completion section and its existing charts. Trace how the currently filtered pathway items and learner counts are provided, then verify the chart against the stated pass-rate calculation. Done means a bar chart shows one pass rate per filtered pathway item on the Item Completion section.